Saving Lettuce Seed

We’ve been trying to grow and offer seed for Cosmo lettuce. But we have only a little bit of experience with saving lettuce seed on our own farm, so it’s challenging to get a good seed crop of a large enough size.

We let the lettuce head up, then bolt, becoming too bitter to eat, then flower, and finally make seed. (Lettuce plants become a lot bigger when they bolt and flower, so before they bolted we made more room by harvesting every other head for eating.)

Although it’s possible to save lettuce seed outside, even in our wet climate, growing it in our high tunnel keeps the rain off of the seedheads. This greatly increases our chances of getting a good germination rate and being able to sell the seed. We’ve put up a rope around the bed, tied at waist height to six posts, so that the lettuce stalks can lean on it and so that the seedheads won’t lie on the moist ground. Nonetheless, our first harvest looked terribly disappointing.

It’s been a wet spring, and this harvest came after a period of much rain and humidity. I thought we had a crop failure – too little seed to be worth the time it would take to separate it from the chaff. I almost gave up. I moved lettuce seed harvesting down on my list of priorities. But the next harvest, after a couple days of dry weather, gave me a pleasant surprise.

This time, when I shook and rubbed the seedheads over my tray, a significant amount of mature-looking seed fell out along with the chaff. However, it seems some of the seedheads dried up before producing good seed. Shaking old, dry seedheads still basically just gave me chaff, not seeds. A day later, there was rain in the forecast, so I collected a small, early harvest.

I was quite surprised that I got so little chaff and so much seed. Of course, even this seed will need to be winnowed and screened to clean off the chaff. Then its germination will need to be tested before we’ll know if we have enough good seed to list this variety.

For more on how to save seeds, see our Seed-Saving for Home Use handout. Later this year I’ll post more information on how to clean seed by winnowing with a box fan.